SC400 no start, no CEL

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Apr 24, 2013 | 08:34 AM

zeus87gn

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Driver

Joined: Jul 2012

Posts: 90

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From: Ms

SC400 no start, no CEL

So our stock 93 SC has been running like a dream come true - lots of power - everything wroking
I had rebuilt the wiring harness back last year, details here
Short of a bad battery cable, there have been no issues whatsoever
Mileage is still pushing 250k on this daily driver

Last saturday she stopped to get some breakfast on her way to work
She came back out and the engine wouldn't start
There is no spark and it appears no fuel is being sprayed either
I don't smell gas at all...even out of the cold tailpipe
First thought was the CPS - changed it out with a new one and got nothing
I checked for DTC with the jumper wire at the connector under the dash and got no CEL flash at all
It doesn't even come on when you turn on the key

Is this a bad ECU?
I will be checking the related fuses this evening - forgot about them
Also will verify FP operation at the turn of the key
Am I missing anything?

Thanks for any help you can be,
Patrick

Apr 24, 2013 | 10:01 AM

Ali SC3

Lexus Champion

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From: CO

sounds like the fuel pump ecu, on the diagnostic terminal you can bypass it to test the pump, I think you jumper +B and FP. if you do that and can start it then its probably time for a new fuel pump ecu or bypass it, search for 12v fuel mod.

Apr 24, 2013 | 12:07 PM

zeus87gn

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Driver

Joined: Jul 2012

Posts: 90

Likes: 1

From: Ms

I read about the fuel pump mod - I thought it was for the forced induction motors
That will cause me to have no CEL light whatsoever?

Apr 24, 2013 | 01:42 PM

1JZPWRD

1JZ Single SC400

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From: Alabama, Roll Tide!

Not sure on the check engine light coming on with this mod, but it is worth a shot to see if it will cure the problem of no start. Just use a paperclip and jump the two points above.

Apr 24, 2013 | 02:18 PM

Ali SC3

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From: CO

Quote:

Originally Posted by zeus87gn

I read about the fuel pump mod - I thought it was for the forced induction motors
That will cause me to have no CEL light whatsoever?

very perceptive. The mod is useful for 2 things. Not sure if it affects the CEL I want to say it wont seeing as it isn't right now.

1 is for keeping constant 12V for forced induction motors at higher boost levels.

2 is for bypassing a failed fuel pump relay which is very common with sc400's and some 300's, although I always recommend replacing the ecu with another one so you keep the safety fuel cutoff features in case of an accident. The bypass will get the car going though and will narrow down your problem if that solves it, then you can search for a replacement fuel ecu relay (PM aliga in the classifieds).

Apr 24, 2013 | 02:48 PM

92SoCal

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From: ca

happened to me earlier this year, did the fuel pump ecu mod and fired up like a champ... i replaced the fuel pump before that and she started up but after 2 days didnt wanna start up again the ECU mod did the trick.. try it before replacing anything